Gripper looms comprise two grippers carried by gripper rods arranged one on each side of the loom to move into and out of the loom shed. One gripper carries the weft thread halfway into the loom shed while the other gripper seizes the thread and pulls it entirely through the loom shed. The movement of the gripper rods into and out of the loom shed takes place freely along a so-called slay sole formed by the reed beam. Thus, the gripper rods must pass over the lower shed warp threads. The lower shed warp threads also pass along the slay sole, but crosswise thereto while the gripper rod passes lengthwise along the slay sole. If the lower shed warp threads are very heavy as is necessary for heavy duty industrial fabrics, they have a tendency to displace the gripper rod upwardly away from a straight linear course. Since these heavy duty fabrics can have a thickness of up to 15 mm, the deflection of the gripper rods can become severe and the proper operation of the loom is no longer assured. Especially the proper transfer of the weft thread from one gripper head to the other is not assured due to the deflection of the gripper rods.